SQL: SELECT & FROM

Spec & Goals 3 min

AQA Spec 3.7.2 — Retrieving data with SELECT … FROM

By the end of this lesson you can:

1. Use SELECT and FROM to retrieve chosen columns.
2. Use SELECT * to retrieve all fields.
3. Predict the result of a simple query against a table.

Warm-Up 5 min

You can now design tables. Next: SQL (Structured Query Language) — the language used to ask a database questions and get data back.

Quick starter

If you wanted just the names of every student, which would you ask the database for — all the columns, or only the Name column?

Key Concept — asking for columns 14 min

SQL (Structured Query Language) is the standard language for retrieving and managing data in a relational database. The most common command retrieves data:

SELECT field1, field2
FROM tableName;

• SELECT — the fields (columns) you want.
• FROM — the table they come from.
• * means all fields: SELECT * FROM Student;
• End each statement with a semicolon ;.

Our Student table

Example queries

SELECT Name, Town FROM Student; returns two columns for every row:

Worked Example — write and predict 12 min

Problem: Write a query to list the StudentID and Mark of every student, then state the result.

SELECT StudentID, Mark
FROM Student;

Result — two columns, all six rows:

To return every field instead, write SELECT * FROM Student; — all five columns, all six rows.

Try It Yourself 12 min

📝 Exam Practice 10 min

Recap & Key Terms 3 min

SQL retrieves data with SELECT fields FROM table;. SELECT chooses the columns; FROM names the table; * returns all columns. With no filter, you get every row. The next lesson adds WHERE to pick rows.

SQL

Structured Query Language — used to retrieve and manage data in a relational database.

SELECT

The SQL keyword choosing which fields (columns) to return.

FROM

The SQL keyword naming the table to retrieve data from.

SELECT *

Returns all fields of the selected records.

Homework 1 min

Task (≤ 15 min): For a Product(ProductID, ItemName, Price) table, write three queries: (a) all fields; (b) just ItemName; (c) ItemName and Price.

-- (a)
SELECT * FROM Product;

-- (b)
SELECT ItemName FROM Product;

-- (c)
SELECT ItemName, Price FROM Product;